The Magic Kingdom at Disney World retained the top spot of theme and amusement parks worldwide with 20.4 million visitors, a 6 percent increase from 2014, according to the report from the Themed Entertainment Association and the economics division of engineering firm AECOM.

The theme-park companies do not publicly break out attendance for their individual parks, so industry executives consider the TEA/AECOM estimates a leading source on visitation.

"The growth we've seen this year is tremendous for a relatively mature industry," said John Robinett, senior vice president of economics at AECOM, in a news release. "Over our 10 years of tracking the industry, we have seen steady improvements in business volume (despite a global recession), the introduction of exciting new technologies and continued internationalization of the attractions world."

The other Disney World theme parks — all in the top 10 of attendance worldwide — reported healthy gains. Epcot, Disney's Animal Kingdom and Hollywood Studios' visitation increased 3 percent, 5 percent and 5 percent, respectively. The three are much smaller draws than the Magic Kingdom. Epcot drew 11.8 million visitors last year. The Animal Kingdom had 10.9 million people walk through its gates. Hollywood Studios attracted 10.8 million guests.

About 25.8 million visitors came to Florida during the second quarter of 2015, an increase of 5.5 percent over 2014's second quarter.

About 25.8 million visitors came to Florida during the second quarter of 2015, an increase of 5.5 percent over 2014's second quarter.

SeaWorld Orlando had a 2 percent increase, bringing in 4.8 million people. The report showed that SeaWorld in San Diego was the only one of the top 20 North American theme parks to experience an attendance decline — 7 percent.

"TEA/AECOM attendance numbers are estimates and not based on actual numbers," SeaWorld Entertainment said in a statement, noting that it reports consolidated attendance annually. Overall, the company — which owns other parks including Busch Gardens — had 22.5 million visitors last year compared with 22.4 million in 2014.

Orlando's water parks also showed healthy gains as well. Orlando has four of the world's top 10 water parks. Disney's Typhoon Lagoon and Blizzard Beach both drew 5 percent more visitors. Those two parks are No. 2 and No. 3 in attendance, respectively. Chimelong Water Park in China is No. 1.

The estimates show 77.2 million people visited Orlando's theme parks last year.

Universal's market share last year was 23.8 percent, a percentage point higher than the previous year. Disney's market share was 70 percent compared with 70.9 percent the year before. SeaWorld's was 6.3 percent.